SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '378e44116bced79230174da127489394506b4d3179c151ee57d25f146d53e406' 
  AND token = 'td4880Is/Ofd+TywXxSHTp6KcohZwbSEZuzIVdDXIOk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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