SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2e3fde168ea5135323b08b971b0531a5441468f2f385b41412e632edfbe7e357' 
  AND token = 'B+GLGF6NWNVKBgkBq6bm6YsmqRUX4rCG3M/tZTjVoNI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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