SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '99ef709ae27ec748151ae1a4e0e89f185db98e8256899d0d9a43882df29de911' 
  AND token = 'u3ssD4scAwzwx4TOVY5QMoPpr+Dy39ygvfTEJtLwR1E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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