SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20b5141bbc976a44f5577c80a3afd5a42ced537e96a7f9588a232b733d7e438c' 
  AND token = 'FSOHknKNHsQFJ9VMB3Ou8bKYZKci98WJeFAr/iQHDmc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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