SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c0497322fac1404ef10f959f73df3178a36be80ad5cff646a0967f06ae9d618d' 
  AND token = 'UHwIRgfXJrq4B3uq3Fhv52LZnnu65gGHEb1qYdK+NI8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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