SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a608dfe556790a9d23a7cf917c6b6fea98b2055a8eae22e8c70f32ed7701d08' 
  AND token = 'cPHfVyMKXMNeoCsmhIDnIr2Mhzbt+V7Oe07oYdZMzP4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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