SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd7473ca1318358de51bb9ede24161692f1f8a3714c96d302892c5876571bfda0' 
  AND token = '4mTi3zhoGkapfmxnBAX7Zz5zpHtbSkf0uTXCEdxYRjo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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