SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '79768ddf1cc670ceec514ade10c53a884d28409b75f35e1eb84682afae35aae9' 
  AND token = 'dpQzHmDusPrA1FWvKWdgU2cLrJ7rA/KoHCDbiBtdXi4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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