SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f108110cfd6f8909b8ef8ab02ef4f49bdcbf4f6c7bf25fa206289f6f9815322a' 
  AND token = 'F/6/fzbkEWOtbmN/5IKepGjJMXfRjnlsnJ+a0E7cHbU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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