SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '213104a544edd8b18a4f0a78754a85feae4d4513f3571aeb689447171101049e' 
  AND token = '6PBSeffcpAANCQ2y++acDakbbjGtxMOBKVNMSFJz7Wg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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