SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8d3568b20efb9b5345139f07d65f890750b588dc1facedcebc1e9e4f394cdc96' 
  AND token = '67DF3wK0FTo9eAmCyJHNstakYSejMeDPPrUBiYzTgQo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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