SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '79b35b9286476ed65efdd4800a3b370df3e14dcf7b9f6196b18d42a56a5c5d00' 
  AND token = 'Jl9NiH/weogh4sdf0VtqFTv6nGJ0ChaTztDb+Gx2oHY=' 
  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"
    }
  }
}