SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'd6d634f79bddb4f0e085267982bd0e759a67a5e76e7f5c0d313484df83593442' 
  AND token = 'L2L+jKIILe2mnt+RC4hOy1dNvDJ+83K3CgqVik9lrMs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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