SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c64e6848175fdbb6f1cd5b37b22b0c0e67acd60ef2db51be3a6eb4f77f9f6d0a' 
  AND token = 'NpSC9/xgi+MsHQsYs9Gq9ycEC+MtNgdbbCD1rC3P/UY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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