SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b21f04b6f41a8d6296cafb0da5f9441470d3b2e3af6450e013e8854f7680e0d9' 
  AND token = 'N5FLaSYnRvmGPqVeuljXgJ/iyE+Oef0oMPUvcwXtjAs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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