SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '16c3cb1fadd74ff24ace2de64058118738de10c315509e2a0a500d98fe71fc83' 
  AND token = 'dK+WBhN+X/ZOiGjkG8YLV1xuGzXtZWExRsLSWtRlOe8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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