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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff82d9c5cbe339d47033cd35e007b9f6816376b4b9cd67d67bc2ea8d2ff8b258' 
  AND token = 'gEjZfUiDibqm1eo+MnOaCGLSds8UOUDqJs+CuU5rz7s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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