SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3661eb63076363358f0ee8eaa9b38134668fad6adcac6ea36b807717b3b968f' 
  AND token = 'twtgaNazJIcEteysiSzCIb24NOQhfwstNXW11tB2KGw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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