SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1ee68f80e076dde5fd2425b388951a6ade651f909758b8bece8a11127b4dd324' 
  AND token = 'B/QCcmRaOUauZYM5KIzTmYX16JzKDCNYhBl/whtlOLo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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