SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7c8d1dd7bb548990f145d15154677176868fb68a68a6f2bec11bf119043f68fb' 
  AND token = 'nChK1RM9LRgXvMiDWVogHIhBW7Inu9dORHrkupTqv00=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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