SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b61a1a1c2ce6a68b8fa74628fb682caf996648d69b5b7559a1121dfed7f2bb7a' 
  AND token = 'xlrDVnV/5EojB2Ks+FG8hBYZBgP6tf3Jx5dwPxddsoE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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