SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '83a887ff6925f813a160be7b2484bf217b68f827fae13eb94a64570c510b19f2' 
  AND token = 'eZ3eGGZktU0tqe3DTOacU5OaTFvQctrmZwPAuF3tbbA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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