SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd8fd4d947052131f7efe41cf804bee2422efee2756a0be51f53dfcf991c16fb4' 
  AND token = 'Tw8aKbnLaQMfJz8sNJwmjszmxo0XPeZTgSpiufnOZ8k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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