SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '426370f5a6609e0b52bdd97aa3bb1461934311b7f17fe27d348855dd1a69ff48' 
  AND token = '8pIMMAavwiE2nQoWGvB4cU3sozsmMgZtklGzU7O+tYo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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