SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f26f1538938fd4f2466374b535385027fde158947dce05971a054b3177815232' 
  AND token = 'i4f+2AnUhcWRX5v4IYKUQ7JRCb/IszIwRWNO3Z/ZYVw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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