SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '49375a975174014653308c5fd184e7686693355165d0c225adc2ad0413413a79' 
  AND token = 'CQgpQgDL8TbFdnRr+MHz9Q81sPX9h341s4ilDRRh+hQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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