SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e76f100e19ee864efca7b991490de4635a2f55ac5ee8db467c949d4f4e3a2321' 
  AND token = 'l+hVHjcBg5IcUmdJs2YfJso7bV21zpiBvZaEqfWM4Xk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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