SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1495a5820c104b7fc1282410463e278cb3050c879d4d27ad0468f598703d4bfa' 
  AND token = 'BXM6mFpOVynGMIu1V4zdbjuJlqLrZ+wsdjdYe9EAWQo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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