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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '136c77c528d59c3504a0f7c69f397280d74c23e0b6f842cd258e4f7d42b2bd56' 
  AND token = 'mqVYUXcruw9x+7w8RBSaWlsdkUS9OKnYNT4i0m377NA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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