SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b77ec7406f2340f7138aa9714d3c4903f1f858c95d706f86ed25005663dbb992' 
  AND token = 'hcVECrDAJiKfCJBJpTKmVy+03/BRUuKa1EHuix5TyUI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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