SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '612e4cdeb1159723db8ce649e6776fbe200d7efe5eda1167a27fb480e18bcdc2' 
  AND token = 'fqvZLtrB3c4q+8rqnr+2nzXIvfbTj6RpUwhDsIkHkwY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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