SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '189f31cc981523bd59c4c1362f69014f0c844d6ae2a6bc0c0efd9c5fdd1d5317' 
  AND token = 'cGMkhh0ToSossHjT3f4rTNEiIOHZKBVekVfInKwpofs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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