SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '284c85c82c39577a1107205ef7a250fbc19d29b0dde5641a3b9d58fd15976ed8' 
  AND token = 'ZZmLSvdCCUF+cO+9EIpPw3bb2JskYHqeQIFVPwLAnG8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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