SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ab19909f3114219fbc25fba3fd409b1a2739fdc6a15b5cd75d4170c19cd5a3ce' 
  AND token = 'm6LqDYIThMiFIzyo8zcFWB3OLZ5nAvhMcedwBj1+/gk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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