SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a46e1fe8375f4d689f0ca026f936f4a9a85912322233b42279035f17714c6778' 
  AND token = 'ezeF89vT/MQQcfTgvjYU6FS4493kx37CKZqgHz33zzI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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