SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '870a85643f52b7d3a7f3047fbd4f1025d70219a6d17868d007eef1d11fa9ba84' 
  AND token = 'QFylMmgGd7ZJUNvmji7vt4s0BQA8uWUo/qLH9pY/gLA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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