SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f9de1c5ff9dfaa3331d5badaadc73136aae7d8914835b1eca663af9782cce1bb' 
  AND token = 'ITkFrd4ea+/+2UE2JvAZsAlvaH3Xybd25mk1ZuTiT+I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00055

JSON explain

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