SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e6f05a12b642e7602bd978f6f546a4e574398114960c67bda186b8efcadf1611' 
  AND token = 'dkA2WA7/Bm7hquUA6KJC8Rv/lTiuSxzuwlhWzbgb1IY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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