SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '875ebe5a9b27da80a7f997b279ca14c35f90f73019f4a9f2247a4a3d07ad3dba' 
  AND token = '4ouVN1R3QAJ39y6k5gn7ZJYUA5jjsxaGRefuY0ENc+M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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