SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f17d5fe624964ae909a575c1bcaf27f53cc0945a5dae3b4b46f4b63272ed7d54' 
  AND token = 'FLmweRnDesclywXGWB4jNrgRkYMl0vegrxbCJfp+3TY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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