SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c7a8c52a81608981010fe21b966f3ef1b8f9614969878830bc9631c41dda082f' 
  AND token = 'xXFfZayZ6VslKiYVFGgu3XxJhXJ8gCAuqBQuBn2uyPM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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