SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '81c2eb4fd4c632a88c95858c9fd108a51e212514035b75aa41469a949abd8b0e' 
  AND token = '6H+6ivSjssTXXeflqcySDmo+b4w6f0a35dWjrfrbz3M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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