SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '29a91421bd6a94a89fd34d3059a580cf7e542dec3cb980823d2c17720f84593e' 
  AND token = 'boXYoBIqYu6I/bG+jczfvj6hVJeNTGrrBA7uZJywkNo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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