SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51459687cdfc00bc2228e50dbfd5fc4d0bfa55bfe9f5f59adf533ba9b7eaddd0' 
  AND token = '1+SZUIKndAIdIBJd1ilmRfMrNZI7XbqU7Mxaej8ymVM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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