SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '338869c11988995f5b9a450b12687b4ae1fac710cafbbbd258571b7983adfa76' 
  AND token = 'GRGNS/dgCzDox6IVgHv78yYhzKKJJZzaj16wBkq/wXo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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