SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7da45a93ac1377031c0efeff6e427e50ec26841cf9d612c23f6d85412c859186' 
  AND token = '6iUfTdd7TbOh+wj2YuUvEtBLr1+aRSHpF1fqkMhT5C4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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