SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'e7ff9675a485592b74ba5c250895f864318f5f7abefedd066b3cfa66c9006c86' 
  AND token = '3mze3+FtLwhlATs3exTQ2EPxhqQzYc77wFfCLrxpvrU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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