SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c66e7a57b77a8cfd1943b50a7cb6af073ca6d603bb0df20f94b2698ff29bd54e' 
  AND token = '0AcSIhR9WID3KJoge4bJmBTfLN44LByTCVydA6kB2Q0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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