SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '749f4fcac70c008a950951ff7e1c55ed322ad68283464b64c3edf4316440427b' 
  AND token = 'kxOrwUaKZrVLhSWIaQB+lBs/SR+FKOiOt2DufZe8M2w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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