SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a2d53629356b400902cb16ff183ba53269d9e2f2840f24cbf9394b7eb4e3dbf' 
  AND token = 'GbFQY/bBm3iJKULnaSJUMjmjnkL4EOm2mfEePkfRgAs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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