SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6de9d5d7337c4f21b3ab0bcd2b8d0edce78c742492f33bbfed05939915405d5' 
  AND token = 'klb9tV7W56Fm1qxB/VtyanrrLUB+pc1kizSfWS2ckJ0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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