SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3d836811a1c3d9664e2f3dd5c2130ae3559dc19d540103d467892ba1cc37719f' 
  AND token = 'cPbEEosCxg+nDNeRyLtYeXxQ2tqFWbLdZTDZZqCqheU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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