SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a37e21d678b991c628788519ffae6242eb43086c69a1d6ddc17598abad843070' 
  AND token = 'vSBvdsj28M1ydyIVv/3XhbuDBZhRaDqtCr8o9hhPIsw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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