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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18b71a309971c5e0185f8ea0f9efeac6766638af1d12518fea507f35f68f6ccc' 
  AND token = 'dTT7GgjMvLXGJIxmX9L8zplJ+lXeUMiOt3u2h3KauSQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}