SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8c6ed8abb72b365d878baf74bf686afd1bc65577f253f81136c44dba95436fa' 
  AND token = 'DdBrFfJ24LjQ9/iTHRZWnAkD+/9RoenyEGhZCp2ri6I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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