SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4e337d1d15697a4494d758cf39838c021109a52461d0281bb408872ce841ba99' 
  AND token = '4RRTyqFndR1luhX4UJJLTu3kKeBA8IUQvRrzDICHmJM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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