SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb6734deb6986d75c4874947070e8160b679ae2acc5cb6cc7cf31233232de51c' 
  AND token = 'rCk8Kvg0O5Y79MJZA2+kvGzUBmuAwPxEfWM1kqex3rQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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