SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8bce6f2b3a69726b525d63e43c02b8f871c68e4757b3aa22dbea63950e47d513' 
  AND token = '0O4QIXYlk+aaQAKN/eRnOZmwVx6SPQ9YqQ2aQnghnwc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00055

JSON explain

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