SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fc2d3c14522007d4f8092afc5406c1b7d301b8a36186af0efaee81ddb9a7bf83' 
  AND token = 'WpskPEPmK4BDRE22GB3kgzqMSIJqKNz3d7S+hCqJqLU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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