SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9d3eaceedf02429d4575c07a7375f8a2042469744daa83998bf721c4a5837191' 
  AND token = '7OvkOL49PZpIg4ySnyY6SK8VYKhOPFAMDKLelf1AThw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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