SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc5a01d8b49e2f4a4857450f75b0fad1be2d42e726148d9f46815ba98fbe1723' 
  AND token = 'xUsXKwTdhoCxZfuFGgvBGJAy2Q5++h+goRgtGNiNmL4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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