SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6165c46fa0f2372a83578307a07dc256b7d2cafb089fb48a763e9fe164e7347d' 
  AND token = 'PwGcUvPUxCXJTj65WKew3hl0F0Qq7VIrxgRdi18Itzg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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