SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5f2511e2b0894ef6630bf1ac6e285ca9c23ab8febd78d074d60d1ba02a5a63a9' 
  AND token = 'DFUC1urWHmPhm7mFTaoctPdh3pMUiGpFx2ac1mkXglQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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