SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5933a3119e81549ea98fcabf854ff729a0e387aa748bb1644a20e23f7eb0ce3d' 
  AND token = 'mkrMM9/QRhlgEcKB0xW+oxVLjUYfXrP3qGMBHleFWWw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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