SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b75ebaff97df454f29019daa3edf309ef45834dfcf1ced649af9a45100b5ba21' 
  AND token = 'dxw/wgBmPYHanIvBJ2TRLLV0WhhCyrdUyo54JElZIAI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00048

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}