SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6088792284065f75c5de9643a84bb30e39e2870cfdb9953c4e8bd01266d2241' 
  AND token = 'XjP73Taby/89LzJOB7+XvGSHjvP83JEppHI8UE/9Bhs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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