SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b4edecc1675162d7383b45c1357889e78d98acca18344aa8ce792a6e1127933' 
  AND token = 'QyhZNWoyU5v1oPv0HnvXkZ1nBphUd0JvVhpf4qNxTDY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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