SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '8a3cf77ce762401bb7ebdd0098735ffe2aba6d8c19eb3f8195ab6a23480da306' 
  AND token = '6MMRTj7Rad2gQzNYvCdWz69Tf2wtT9nvnsK94NET+Fs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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