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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e5b5f9ef7c60b0a7c830e2d0f5100bff41cda39fea11658d0aeb4b9b1e9a523' 
  AND token = 'q6ZEtpTLcLx5EDdjCF+3sZjvjgT/GRn9hp7dMOMvlZA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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