SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c27388248ead8d11c1388d8ef254120380b4bd93360626646eb7ba08afede846' 
  AND token = 'KUABqCuDHJ+JTWd9sKlANwBRboLRdpgz93HUaArLHtk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00067

JSON explain

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