SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f9dda4bb7a38d213b5bebc52f83819eb1afea88adb5852947f651291c566f369' 
  AND token = 'tCaJB6ZYpkMp8lpNcmD8eJ5U7euFv9fTha7VuHHMHoc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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