SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '135785b0d8a588ca7f4eebee6e637c0db0c66f78784ae313dc725da709789c2d' 
  AND token = 'xQkEC0TbIvroCYyGFUZohOnxL/guM6ccQ7YDknDArFY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}