SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c78d776205a5585e4aaca6103ec502927533533ad989a859b453c6a7a4a503cd' 
  AND token = 'hTP2CqEGYocCiVSrpZMq7ymi0lNiDWkPz2pUfcSipTU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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