SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '25a73f95acc5d2f7f7900fad771012a42c508e97e4b53e5a326843385a513fe3' 
  AND token = '6EoErnibF40uklsg8UtdMKqXnVzLYCt/DSMgRO2XhBU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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