SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6cb76740824ad9dd47945360aae265b4ba233a78c98bcf3c3b2493207637af00' 
  AND token = '0GEuDUj1H475Nk+o/IZRJk8lJB9j5yXTuKQvmNZJVng=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00048

JSON explain

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