SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3927866d2b04854b3fea36c76360c78aa6dd30240d42c711e594d43fd87fa4f3' 
  AND token = 'FaaL35CGfURT+WVlWg0Nq07JnxQ7xv32BhMrxp5Dspw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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