SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f45960e7e412e864196396617195344640da5af42b093b5366518a9eb451cbea' 
  AND token = 'MMMGUIPJDzI4yviPO11OcCeT6q8dkcpToq3gRCZfDTo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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