SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b276eaf93850cf7d233cf098aa0b87e11bd7975dd2d704572312e85767ba6876' 
  AND token = 'N8ps737NZzoCFqrgPA2WlJXnZ53/p/UXoLcWG3eL/QU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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