SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b08fcbe9806fefbef59200c333b1fd257ae858d4bd96d0541cffe1c40fe2d908' 
  AND token = 'LOq9P/DBhAffVrKM/5WfIk+6vkA7MRRF/wrAscfV4Tk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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