SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1286798f91dce7a360e44968f0724e50b53b9d0165ca6f9f4885198d0d3c7a40' 
  AND token = 'H6NzE44vkiPENcMNyXvitV690bIUNXKKotSSXALlcjQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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