SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f3a6bea4fe96db77198f65b8d8e66238274fa4a6c8c38ee8db54289093490ba0' 
  AND token = 'mF39BGtbIf3vuYCcTyYJ+xxd6aPu57F3gUS/yygFGqc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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