SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a9bb9892dcfc904be7f6b6deb8564f70f3850331ff397b19aad9d9778daf2951' 
  AND token = 'JKu1SOpKcldShJ8mbpkXh6loHSKaxK7bu0eul4kVOC8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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