SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe4b588615a91e93e0775c269e639cf8d62aed45e24dfb1f2897c2b3486ae390' 
  AND token = 'Vz8uPDROCcLtuglNHBdkUuTIbfRGOeMm7yW7bkGc+TI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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