SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '28da73671118f4fecf0aa4a855bfb87f3bca6b875b22f5cd46d9489ba8f1e1fc' 
  AND token = 'chNlvkJJjMf6HyTFELekk0ACIdFixOKxErAxP5SzKcM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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