SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c830ac25f337f2d7defbdec6a3a3ebb9d1b65384967453503a4d11923670d95b' 
  AND token = 'cr2cwlx/7ERcUoIzUVuMsaHuxgjDSlYJKHpdX9oR60Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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