SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c141fd6131971ef6bd7590b816a075734d2a41a270cf7931ff509c6d67bc514' 
  AND token = 'QqiVYFxxV6BBnQQxtkOsx4f5gjgbSAbXiDgnbYzdTv8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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