SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a73a715fc8e1ff879f4e7850563393dd71cdcf3b6d435994e34dce23c8a29f43' 
  AND token = 'glVAEfo4JgdscUK9tL7UjC2g54nvw0GkkcZKOxHesOk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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