SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0c815f2cbf5798f645414f7c0d5940734206c31f851e5dabb4755de87e1e2ac4' 
  AND token = 'F0SjC2XuDGxcHPK9LP7WIxkVDn/ZUJJtmf5G0gyYAhQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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