SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78b8516f8146be4d735ecaab6d4aae5cb6c872253f2ce8c767be311c054e552e' 
  AND token = 'MTQm66FforedkEa9kv65VQzDLYGATtonNU6bvPXEldE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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