SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1394469abf23526cab44ff5b2875e6a8029bf24e7804a14b2c8da6237743854b' 
  AND token = 'R6vBD2VFzwZQGq0mXybFbqwAvi/u+KOGNRTbJpy0HaY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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