SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a88754c6bdcdd22e305d4c4253c5999f87656147ce26971cd49501e34e1d3540' 
  AND token = 'iJznqBvHxpyXLd/YVxGRgHZVOet3F46Ipk5BCPocAzA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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