SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7c2fef53068111148106d3f9e76d0181ae9f20652d6363374459090090e023df' 
  AND token = 'l4WMiYoReqi4mdxHpseGfJOBrQrUVq9bAvAP3XWbMb0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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