SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '21f5f0e223e72d63a9ad11290c480e043d92341addc6c806a03700f333e158f6' 
  AND token = '4R2jtIP57SweMtP0Zh9tR6daRqKjavhUV1NpsjSA3kw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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