SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3e8293d3e3add27961b74d4f5a14b263416ad08b7a48c0e49ebeb6b840e6cb27' 
  AND token = '1BuWngwJHlhwBj5YqxrDwHvoeK4TCjWxDC8unDZ+Jw0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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