SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '28315c5d856df6315c0b543fb86f78659bd4cfee83201a69bf697902f2cd0689' 
  AND token = 'uEcv7rL8jYqWT+BIM9IoXQ0Iw+74wVJOTNmaW0XUwuU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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