SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a5143b2c9be2cf54541751e866e625e3f785591a4db3511c383253539b53c616' 
  AND token = 'ZhQhmGKGTSogyeBoUW/4UJCQFv//V3dVdw/1sW4jCzE=' 
  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"
    }
  }
}