SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42ec1c97f4bdeb4be16d6941ffafc8a94529af5f9d22423b1c854796380effe3' 
  AND token = 'lXk9JLJpq7CFpxdpJIZDV2I0Qdu2CmI1CZz8Qg4QiWA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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