SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9a53f7cb427d02732e37315ed0fc0528acb5ddf34ada0ba55a1bbf084a991289' 
  AND token = 'h2UZGDXILl+Rt7aQwt2jA1XHzygc+MM7ZJK760IFKkQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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