SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '514b16ebce9c716498cebd14518de623ae980ef4e147295cf67802c18b4e79e8' 
  AND token = 's3iTY/q3aanZnPZhDzIzouMQSEX5PC7QZ9PB8Tc1ifQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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