SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b82d827ccc943bf0cc605ba198ca67838d4059b0fc5647bb2836577bc7a7ffa0' 
  AND token = 'fxyfruv8YEI40XkE/rrpZN+ThPLYUriRXBZb0i3CeJg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00013

JSON explain

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