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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c9f38753d2b8fde65dd04429d0836cfccb8cc9fbb7aa6a485c0c737340e796f6' 
  AND token = 'Nt4mjTSWV7sWvfyXVsp4pGkhyvQ/xLI9jibfrsZL4Tw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}