SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4abaf6b54e4cbad4aebcea5fddba1fe94ec093048abdff0563e39faf5632b688' 
  AND token = 'UdsD5zizdBY+wIzQY2hhjwyuzwhGhA9zOAylBknsMNo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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