SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2cb5bbab010e085a2802c39cca3251737a463bed27141effa3528448c91db6d8' 
  AND token = 'dia1tnElYHio/JfPOdo22EGYPTxpgX+GsK5HHmmip4w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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