SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2088fa50686f0a3812496d509724e60b0aaf314c44c153489a9f6864f818347c' 
  AND token = '0IphEl+rgz/LcfZph3iIWvFP8KY2kpxNLOrQ6RwfBnM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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