SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '789b2744e8639d4273b52cb5557c962f6b41c9f358bbe329e6b91d3164b1bb4f' 
  AND token = 'oXG35k+5qwNqjg3Qwr0eug5mzlvpThjd246o1KMYP/s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}